Advances in Treatment of Obstructive Hypertrophic Cardiomyopathy - Episode 7
Experts in cardiology review invasive treatments, challenges with HCM treatments, and how to optimize treatment for patients.
James Januzzi, MD: Let’s talk about unique challenges with treatment. You’ve already mentioned beta-blockers and their intolerances, calcium channel blockers, high dose, constipation, edema.
Steve R. Ommen, MD: Drug interactions with the calcium blockers.
James Januzzi, MD: Drug interactions, absolutely. The risk for rhabdomyolysis with statins, for example. Disopyramide is a drug that I’m sure many viewers aren’t familiar with. As you said, Marty, I’ve seen transformational reactions in a positive way. I had an elderly woman with HCM [hypertrophic cardiomyopathy] in whom everything had failed. She felt great on disopyramide but then she developed urinary retention. Why did that happen?
Martin S. Maron, MD: Disopyramide has a mechanism of action that can have parasympathetic adverse effects. Those generally take the form of dry eyes, dry mouth, and prostate hypertrophy in men. It can have urinary retention. Those are your most common adverse effects due to the parasympathetic issue. It can be responsible for having to stop the use of the drug in a small percentage of patients. That said, there are drugs that can counter the parasympathetic adverse effects of disopyramide. Pyridostigmine is the one that I’m talking about that can be used there too. In patients who are really stuck, that’s an option.
James Januzzi, MD: That’s useful. I realize this is a crazy question and the answer could be a very simple “No,” but do you ever utilize medications that increase afterload in your patients? If someone has a really intractable outflow gradient, do you ever use things like midodrine or other drugs?
Steve R. Ommen, MD: Sometimes in the acute setting you might. If a patient ends up in the ICU [intensive care unit] and they’re septic and their SVR [systemic vascular resistance] is down, you might consider using phenylephrine or midodrine in those situations to improve that outflow. At the same time, you’re giving beta-blockers, so it seems—
James Januzzi, MD: Pushing and pulling.
Steve R. Ommen, MD: It seems like pushing and pulling at the same time.
James Januzzi, MD: The reason why I ask and why I know the answer was “No” is because in that situation with intractable gradients, you typically turn to myectomy. Why don’t we talk about surgical vs catheter? Why don’t each of you take one? You can choose whichever one you prefer.
Martin S. Maron, MD: Do you have a preference?
Steve R. Ommen, MD: No, go for it.
Martin S. Maron, MD: Steve, maybe you’ll take on myectomy. I’ll talk about the less invasive catheter-based approach of alcohol septal ablation, which is a procedure that has now been around for almost 20 years, if you can imagine.
James Januzzi, MD: We were fellows when it started.
Martin S. Maron, MD: Right. It’s amazing. It feels like almost yesterday, but it’s been around quite a long time.
John A. Spertus, MD, MPH: It was 30-plus years ago, but anyway.
Martin S. Maron, MD: Who’s counting? It’s matured like all procedures. Here’s the deal: it’s still catheter-based, so it’s usually femoral artery access where the catheters advance into the coronary as we usually find the first or second septal perforator and a low amount of alcohol is injected to cause a localized control area of damage that then thins the muscle, usually the basal septum. By thinning, which usually occurs over a couple of months after the procedure, that widens the outflow tract, eliminates these abnormal hemodynamic forces which are responsible for subaortic obstruction in HCM, and that improves symptoms. The reality is the data are very good. It results in a substantial improvement in heart failure symptoms in 90% of patients who undergo that procedure.
James Januzzi, MD: Since you and I grew up in this era, early on there were concerns raised by the people who do surgical myectomy—which we’ll get to in a second—that by creating an ischemic scar in people who might be prone to arrhythmia, that this might increase arrhythmic complications. We’ve got 20-plus years of experience, so what’s the answer to that?
Martin S. Maron, MD: The answer is that there’s no definitive evidence that alcohol septal ablation increases sudden death risk through increasing ventricular tachyarrhythmias.
James Januzzi, MD: OK, that’s very useful. That’s 1 option, and surgery is the second. I’m going to ask both of you about when you choose one vs the other.
Martin S. Maron, MD: Let me just add 1 other point about alcohol ablation because it’s an important differentiator in terms of myectomies. There’s still today, even in the most contemporary view, a greater risk of heart block with alcohol ablation. The risk of complete heart block from the alcohol ablation is about 10%, even in experienced hands.
James Januzzi, MD: Why is that?
Martin S. Maron, MD: That has to do with distribution of the alcohol. What you can control is limited. You don’t know where the bundles are. The way that procedure is, there’s increased risk for heart blockage.
James Januzzi, MD: Because of the specialized conduction system in the upper septum.
Martin S. Maron, MD: That’s right. Even with contrast.
James Januzzi, MD: Even with contrast, which we inject typically to guide, we see heart block. We see left bundle branch block maybe more commonly with surgical myectomy. Surgical myectomy is a remarkable surgery.
Steve R. Ommen, MD: It really is. It’s been around for 60 years. Shortly after HCM was first described, Dr [Andrew Glenn] Morrow, working with Dr [Eugene] Braunwald, came up with a way to treat patients who are having symptoms due to this muscular obstruction. This is an operation that’s performed through an aortotomy. It’s important for patients to know that we don’t cut through their heart. We cut through the aorta and the surgeon operates looking through the aortic valve. They can see the bulging muscle and the contact patch on the septum where the mitral valve keeps hitting it, and the surgeon can go in there and resect the muscle. It’s a short cross-clamp time procedure. It’s a 5-day hospital stay for most patients. We quote patients a 95% success rate with the operation.
James Januzzi, MD: How do you define success?
Steve R. Ommen, MD: We define success by the patients saying they were glad they had the procedure because they can do more on less medications.
James Januzzi, MD: Perfect. Keeping it patient-centered. That’s good.
Steve R. Ommen, MD: The rate of repeat myectomy is less than 2%, and usually that was either an inadequate myectomy the first time or it was done in a child and somatic growth couldn’t be accounted for at the time. An adequate myectomy is a 1-time procedure for patients. As far as complication rates at the experienced centers, the mortality rate is less than half a percent, stroke rate is less than half a percent, and pacemaker rate is about 1% to 2% in patients getting surgical myectomy.
James Januzzi, MD: That’s very useful.
Transcript Edited for Clarity